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The lanthanite crystal structure consists of layers of 10-fold coordinated REE-oxygen (O) polyhedra and carbonate (CO 3 2−) groups connected by hydrogen bonds to interlayer water molecules, forming a highly hydrated structure. [8]
The lanthanide (/ ˈ l æ n θ ə n aɪ d /) or lanthanoid (/ ˈ l æ n θ ə n ɔɪ d /) series of chemical elements [a] comprises at least the 14 metallic chemical elements with atomic numbers 57–70, from lanthanum through ytterbium.
Lanthanum is rarely the dominant lanthanide found in the rare earth minerals, and in their chemical formulas it is usually preceded by cerium. Rare examples of La-dominant minerals are monazite-(La) and lanthanite-(La). [50] Production of Lanthanum from Monazite sand. The La 3+
Lanthanide metals react exothermically with hydrogen to form LnH 2, dihydrides. [1] With the exception of Eu and Yb, which resemble the Ba and Ca hydrides (non-conducting, transparent salt-like compounds),they form black pyrophoric, conducting compounds [6] where the metal sub-lattice is face centred cubic and the H atoms occupy tetrahedral sites. [1]
The rare-earth elements (REE), also called the rare-earth metals or rare earths, and sometimes the lanthanides or lanthanoids (although scandium and yttrium, which do not belong to this series, are usually included as rare earths), [1] are a set of 17 nearly indistinguishable lustrous silvery-white soft heavy metals.
The ammonium chloride route refers to a general procedure to produce anhydrous lanthanide chlorides. The method has the advantages of being general for the 14 lanthanides and it produces air-stable intermediates that resist hydrolysis.
The lanthanide contraction is the greater-than-expected decrease in atomic radii and ionic radii of the elements in the lanthanide series, from left to right. It is caused by the poor shielding effect of nuclear charge by the 4f electrons along with the expected periodic trend of increasing electronegativity and nuclear charge on moving from left to right.
La 2 O 3 powder. Lanthanum oxide is a white solid that is insoluble in water, but dissolves in acidic solutions. La 2 O 3 absorbs moisture from air, converting to lanthanum hydroxide. [2]